Motor assembly method with an integrated flexible printed circuit

ABSTRACT

The present invention provides a motor assembly method for mounting to a base. The motor assembly includes a stator assembly having a plurality of stator teeth. Each stator tooth is configured to support a stator coil. The motor assembly also includes a flexible printed circuit having top and bottom surfaces and an end portion. The end portion is affixed to the stator assembly at the top surface. The bottom surface is affixed to the base.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a divisional of and claims priority of U.S.patent application Ser. No. 11/209,438, filed Aug. 23, 2005, the contentof which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to data storage systems. Inparticular, but not by limitation, the present invention relates to amotor assembly for a data storage system.

BACKGROUND OF THE INVENTION

A typical data storage system includes a rigid housing having a basedeckand top cover that encloses a variety of components. The componentsinclude one or more discs having data surfaces that are coated with amagnetizable medium for storage of digital information in a plurality ofcircular, concentric data tracks. The discs are mounted on a spindlemotor. In general, spindle motors are mounted and secured to a base of adisc drive with screws and corresponding threaded holes using a bracketmounting. The spindle motor causes the discs to spin and the datasurfaces of the discs to pass under respective aerodynamic bearing dischead sliders. The sliders carry transducers, which write information toand read information from the data surfaces of the discs.

Recently, there has been a rapid increase in the production of smallerand lighter weight drives in the disc drive industry. The demand toreduce the physical size of disc drives has caused the diameter of thediscs in the disc drive to decrease as well as a decrease in the amountof discs in the disc drive. As disc dimension becomes smaller and theamount of discs in the disc drive are reduced, so has the relativeheight of the disc drive become smaller. Therefore, a spindle motor thatcauses the discs to spin can only occupy a space that conforms tocertain predetermined height requirements.

The use of screws and a mounting bracket are no longer a viable way ofmounting a spindle motor to a base of a disc drive. The use of screwsand a mounting bracket require more height then is allowed by the heightconstraints of the enclosure of a small form factor disc drive. Inaddition, methods of mounting a spindle motor to a base of a small formfactor drive are difficult and costly. In particular, component parthandling and component alignment have become increasingly difficultbecause of the space constraints.

Embodiments of the present invention provide solutions to these andother problems, and offer other advantages over the prior art.

SUMMARY OF THE INVENTION

The present invention provides a motor assembly for mounting to a base.The motor assembly includes a stator assembly having a plurality ofstator teeth. Each stator tooth is configured to support a stator coil.The motor assembly also includes a flexible printed circuit having topand bottom surfaces and an end portion. The end portion is affixed tothe stator assembly at the top surface. The bottom surface is affixed tothe base.

The present invention also provides a method of assembling a motor to abase. The method includes providing a stator assembly having a pluralityof stator teeth configured to support a stator coil and providing aflexible printed circuit having top and bottom surfaces and an endportion. The method further includes affixing the end portion to thestator assembly on the top surface of the flexible printed circuit. Thebottom surface of the flexible printed circuit is affixed to the base.

The present invention also provides a motor assembly. The motor assemblyincludes a flexible printed circuit having a first surface and a statorassembly deposited on the first surface of the flexible printed circuit.The stator assembly includes a stator yoke and a plurality of statorteeth that extend from the stator yoke. Each stator tooth has a topportion and side portions. The motor assembly also includes a set of setof staple-shaped stator conductors deposited on the top portion of eachstator tooth such that each of the sets of staple-shaped conductors areadjacent the top portion and the side portions of each stator tooth.Furthermore, the motor assembly includes a plurality of patterns ofconductor traces included in the flexible printed circuit. Each patternof conductor traces is configured to electrically couple to the set ofstaple-shaped stator conductors that are deposited on each stator toothto form a stator coil.

Other features and benefits that characterize embodiments of the presentinvention will be apparent upon reading the following detaileddescription and review of the associated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a top perspective view of a data storage system.

FIG. 2 illustrates a top perspective view of a motor subassembly inaccordance with an embodiment of the present invention.

FIG. 3 illustrates a partial sectional view of a motor assemblyincluding the motor subassembly illustrated in FIG. 2 in accordance withan embodiment of the present invention.

FIG. 4 illustrates a top perspective view of a motor subassembly inaccordance with an embodiment of the present invention.

FIG. 5 illustrates a partial sectional view of a motor assemblyincluding the motor subassembly illustrated in FIG. 4 in accordance withan embodiment of the present invention.

FIG. 6 illustrates a top perspective view of a flexible printed circuitin accordance with an embodiment of the present invention.

FIG. 7 illustrates a top perspective view of a portion of a motorsubassembly including the flexible printed circuit illustrated in FIG. 6in accordance with an embodiment of the present invention.

FIG. 8 illustrates a top perspective view of a motor subassembly that isillustrated partially in FIG. 7 in accordance with an embodiment of thepresent invention.

FIG. 9 illustrates an enlarged perspective view of one of the statorteeth illustrated in FIG. 8 in accordance with an embodiment of thepresent invention.

FIG. 10 illustrates an enlarged perspective view of the stator coilillustrated in FIG. 9 in accordance with an embodiment of the presentinvention.

FIG. 11 illustrates a partial sectional view of a motor assemblyincluding the motor subassembly illustrated in FIG. 8 in accordance withan embodiment of the present invention.

FIG. 12 illustrates a top perspective view of a motor subassembly inaccordance with an embodiment of the present invention.

FIG. 13 illustrates a partial sectional view of a motor assemblyincluding the motor subassembly illustrated in FIG. 12 in accordancewith an embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1 is a top perspective view of data storage system 100 in whichembodiments of the present invention are useful. Disc drives are commondata storage systems. Disc drive 100 includes a basedeck 102 and a topcover (not shown). Disc drive 100 further includes a storage medium 106,which is mounted on a spindle motor 105 by a clamp 108. As illustratedin FIG. 1, storage medium 106 includes a plurality of individual discs107, which are mounted for co-rotation about central axis 109. However,disc drive 100 can also include a single disc that is mounted to spindlemotor 105 by clamp 108 or other types of clampless devices. Each discsurface has an associated slider 110, which carries a read/write headfor communication with the surface of the disc.

Each slider 110 is supported by a suspension 112 which is in turnattached to a track accessing arm 114 of an actuator mechanism 116.Actuator mechanism 116 is rotated about a shaft 120 by a voice coilmotor 118, which is controlled by servo control circuitry withininternal circuit 130. As voice coil motor 118 rotates actuator mechanism116, slider 110 moves in an arcuate path 122 between a disc innerdiameter 124 and a disc outer diameter 126. The present inventionprovides embodiments for mounting a spindle motor to a small form factordisc drive efficiently and cost effectively.

Recently, there is an increasing demand to design smaller and lighterdisc drives. Small form factor drives have restricted heightlimitations. A spindle motor can only occupy a predetermined height. Itis also increasingly difficult and costly to mount a spindle motor to asmall form factor disc drive because of these size constraints.

FIG. 2 illustrates a top perspective view of a motor subassembly 201 inaccordance with an embodiment of the present invention. Motorsubassembly 201 includes a flexible printed circuit (FPC) 202 and astator assembly 204. FPC 202 has a top surface 210 and a bottom surface(hidden from view). FPC 202 includes an end portion 206 and a pathwayportion 208. End portion 206 accommodates stator assembly 204. Pathwayportion 208 provides a pathway for an interconnect layer, integrallyformed in FPC 202, to couple stator assembly 204 to a remotely locatedelectrical connector for ultimate coupling to a printed circuit board(PCB). The interconnect layer will be discussed in detail with referenceto FIG. 3.

Stator assembly 204 includes an annular stator yoke 205 integrallyformed with a plurality of symmetrically and radially arranged statorteeth 212. Each stator tooth 212 is configured to support a stator coil214. As illustrated in FIG. 2 and in one embodiment, end portion 206 ofFPC 202 has an annular top surface area such that the end portionincludes an outer diameter 211 and an inner diameter 213. In oneembodiment, end portion 206 is affixed with an adhesive to statorassembly 204 at top surface 210 between inner diameter 213 and outerdiameter 211. However, end portion 206 can be affixed to stator assembly204 with other materials. For example, end portion 206 can be affixed tostator assembly 204 with solder.

FIG. 3 illustrates a partial sectional view of a motor assembly 200including the motor subassembly 201 illustrated in FIG. 2 in accordancewith an embodiment of the present invention. As illustrated in the FIG.3 embodiment, FPC 202 is adhered to stator assembly 204 with an adhesive216. However, as previously discussed, FPC 202 can be affixed to statorassembly 204 with other materials. In addition, FPC 202 can be affixedto spacers, which then adhere to stator assembly 204. Such spacers arelocated near inner diameter 213 and/or located near outer diameter 211of FPC 202 and can be made of an insulating material.

Stator assembly 204 includes stator yoke 205, stator tooth 212 andstator coil 214. As illustrated in FIG. 3, stator assembly 204 is formedin a layered stack of magnetic steel laminations that are wound withwire. The layered stack of steel is coated with an insulative coatingprior to winding. In addition, FIG. 3 also illustrates a base 226 inwhich FPC 202 is affixed to. In one embodiment of the present invention,base 226 is a basedeck of a data storage system. However, those skilledin the art should recognize that the present invention can beincorporated in other types of systems.

Motor assembly 200 also includes a simplified illustration of a rotorassembly 221. Rotor assembly 221 includes a rotor 222 and an annularmagnet 224. Rotor assembly 221 is centrally located and mounted on base226 such that stator assembly 204 and the inner diameter 213 of endportion 206 are spaced apart from and positioned around rotor assembly221. In operation, stator coils 214 generate a magnetic flux thatinteracts with annular magnet 224 to thereby operably rotate rotor 222.Rotor 222 includes details not specifically depicted in FIG. 3, such asa bearing in between rotating and stationary assemblies. Rotor 222 alsoincludes mounting provisions on the rotating assembly to support a load,such as a disc in a data storage system.

Motor assembly 200 also includes a flux shield 218 and an insulatinglayer 220. In one embodiment, flux shield 218 and insulating layer 220are affixed to a top portion 244 of stator coil 214 with an adhesive. Ina data storage system, flux shield 218 and insulating layer 220 assistin insulating discs or media from magnetic fields created by statorassembly 204 and magnet 224. Flux shield 218 and insulating layer 220are adhered to stator coil 214 which creates a “sandwich” potting ofstator coils to thereby mute acoustic output. Those skilled in the artshould recognize that other embodiments of the present invention caninclude a motor assembly without a flux shield.

As illustrated in detail in FIG. 3, FPC 202 includes a plurality oflayers. FPC 202 includes a cover layer 230 formed of plastic. However,it should be noted that other types of materials can be used. Asdiscussed above, FPC 202 also includes an interconnect layer 232adjacent cover layer 230. Interconnect layer 232 includes a plurality oflayers of traces or a single trace layer for routing all phases of themotor, such as metallic traces in one embodiment, or, for addedstiffness and/or lower resistance in another embodiment, heavy gagecopper traces. Cover layer 230 provides a plurality of openings, such asopening 234, for exposing and allowing the traces of interconnect layer232 to electrically couple to wire leads 233 of stator coil 214.Although not specifically illustrated in FIG. 3, in one embodiment,interconnect layer 232 includes layers of traces for each phase of themotor assembly with insulating layers in between. For example, in athree-phase motor, a stator assembly may have nine stator teeth eachsupporting a stator coil. Other numbers of motor phases and stator teethare possible and are known by those skilled in the art. A first layer oftraces in the interconnect layer are coupled to three stator coils thatare evenly spaced from each other. A second layer of traces in theinterconnect layer are coupled to three different stator coils that areevenly spaced from each other. Still further, a third layer of traces inthe interconnect layer are coupled to the three remaining stator coilsthat are evenly spaced from each other.

Stator coil 214 is electrically coupled to one of the layers of tracesof interconnect layer 232 with a solder joint 236. Such solderconnections minimize wire routing. The layers of traces included ininterconnect layer 232 electrically couple each stator coil 214supported by each stator tooth 212 to a remotely located electricalconnector through pathway portion 208 (FIG. 2) and ultimately to aprinted circuit board (PCB) such that stator coils 214 can generatemagnetic fields.

FPC 202 also includes a stiffener layer 238. Stiffener layer 238 isadjacent interconnect layer 232 and located on an opposing side of theinterconnect layer from cover layer 230. Stiffener layer 238 is made ofan insulating material that imparts rigidity in FPC 202. For example,stiffener layer 238 can be a metallic layer such as aluminum separatedfrom interconnect layer 232 by an additional insulating layer or anon-metallic layer such as polyamide materials. Those skilled in the artshould recognize that other types of materials having similar propertiescan be used.

Motor assembly 200 is configured for attachment to base 226. In oneembodiment of the present invention, FPC 202 includes an adhesive layer240. Adhesive layer 240 allows flux shield 218, stator coil 214, statorteeth 212 and FPC 202 to be affixed to base 226. In such an embodiment,adhesive layer 240, such as a layer of pressure sensitive adhesive(PSA), also includes a liner and is formed adjacent stiffener layer 238on a bottom surface 241 of FPC 202. In use, the liner is peeled back andremoved to expose the adhesive for attachment. However, motor assembly200 can be affixed to base 226 in other manners. For example, adhesivelayer 240 can be replaced with a separately applied adhesive or epoxy.

Therefore, FPC 202 is used as a positioning and attachment basis ontowhich stator assembly 204 can be installed into a data storage systemquickly and inexpensively. During manufacture and before being affixedto base 226, motor assembly 200 is radially aligned through fixturingand tacked or partially cured using the adhesives described above. Forexample, the adhesive used to affix flux shield 218 and insulating layer220 to stator assembly 204 and the adhesive used to affix the statorassembly to top surface 210 of FPC 202 are partially cured. Aftertacking, motor assembly 200 can be fully cured in an oven.

FIG. 4 illustrates a top perspective view of a motor subassembly 301 inaccordance with an embodiment of the present invention. Motorsubassembly 301 includes a FPC 302 and a stator assembly 304. FPC 302has a top surface 310 and a bottom surface (hidden from view). FPC 302includes an end portion 306 and a pathway portion 308. End portion 306accommodates stator assembly 304. Pathway portion 308 provides a pathwayfor an interconnect layer, integrally formed with FPC 302, to couplestator assembly 304 to a remotely located electrical connector forultimate coupling to a PCB. The interconnect layer will be discussed indetail with reference to FIG. 5.

Stator assembly 304 includes an annular stator yoke 305 integrallyformed with a plurality of symmetrically and radially arranged statorteeth 312. Each stator tooth 312 is configured to support a stator coil314. In comparison to the embodiment illustrated in FIG. 2, theembodiment illustrated in FIG. 4 includes an end portion 306 having acircular top surface area such that the end portion includes an outerdiameter 311. Unlike FPC 202 of FIG. 2, FPC 302 does not include aninner opening. In one embodiment, end portion 306 is affixed with anadhesive to stator assembly 304 at top surface 310. However, end portion306 can be affixed to stator assembly 304 with other materials. Forexample, and as discussed in FIG. 2, end portion 306 can be affixed tospacers which are adhered to stator assembly 304. End portion 306 canalso be affixed to stator assembly 304 with solder.

FIG. 5 illustrates a partial sectional view of a motor assembly 300including the motor subassembly 301 illustrated in FIG. 4 in accordancewith an embodiment of the present invention. As illustrated in the FIG.5 embodiment, FPC 302 is adhered to stator assembly 304 with an adhesive316. However, as previously discussed, FPC 302 can be affixed to statorassembly 304 with other materials.

Stator assembly 304 includes stator yoke 305, stator tooth 312 andstator coil 314. As illustrated in FIG. 5, stator assembly 304 is formedin a layered stack of magnetic steel laminations that are wound withwire. The layered stack of steel is coated with an insulative coatingprior to winding. In addition, FIG. 5 also illustrates a base 326 inwhich FPC 302 is affixed to. In one embodiment of the present invention,base 326 is a basedeck of a data storage system. However, those skilledin the art should recognize that the present invention can beincorporated in other types of systems.

Motor assembly 300 also includes a simplified illustration of a rotorassembly 321. Rotor assembly 321 includes a rotor 322 and an annularmagnet 324. Rotor assembly 321 is centrally located and mounted on FPC302 such that stator assembly 304 is spaced apart and positioned aroundrotor assembly 321 on end portion 306.

Motor assembly 300 also includes a flux shield 318 and an insulatinglayer 320. In one embodiment, flux shield 318 and insulating layer 320are affixed to a top portion 344 of stator coil 314 with an adhesive. Asdiscussed above, flux shield 318 and insulating layer 320 assist ininsulating discs or media in a data storage system from magnetic fieldscreated by stator assembly 304 and magnet 324. Flux shield 318 andinsulating layer 320 are adhered to stator tooth 304 which creates a“sandwich” potting of stator conductors to thereby mute acoustic output.Those skilled in the art should recognize that other embodiments of thepresent invention can include a motor assembly without a flux shield.

As illustrated in detail in FIG. 5, FPC 302 includes a plurality oflayers. FPC 302 includes cover layer 330 that forms top surface 310 andincludes a plurality of openings 334 for exposing and allowinginterconnect layer 332, adjacent the cover layer, to electricallyconnect to lead wires 333 of stator coil 314 with a solder joint 336 andto couple to rotor 322. Besides interconnect layer 332 including tracesfor each phase of motor assembly 300, interconnect layer 332 can alsoinclude at least one trace for coupling to rotor 322. Interconnect layer332 can also include a ground trace. In one embodiment, rotor 322 isaffixed to end portion 306 of FPC 302 with solder 325 such that rotor322 can be electrically coupled and electrically grounded tointerconnect layer 332 of FPC 302. However, those skilled in the artshould recognize that other configurations are possible. For example,rotor 322 can be affixed to end portion 306 and electrically coupled tointerconnect layer 332 with an electrically conductive adhesive. FPC 302also includes a stiffener layer 338 adjacent interconnect layer 332 asdiscussed in the description related to FIG. 3.

Motor assembly 300 includes an adhesive layer 340 that allows fluxshield 318, stator coil 314, stator tooth 312 and FPC 302 to be affixedto base 326. In such an embodiment, adhesive layer 340, such as a layerof PSA, also includes a liner and is formed adjacent stiffener layer 338on a bottom surface 341 of FPC 302. In use, the liner is peeled back andremoved to expose the adhesive for attachment. However, motor assembly300 can be affixed to base 326 in other manners. For example, adhesivelayer 340 can be replaced with a separately applied adhesive or epoxy.

Therefore, FPC 302 is used as a positioning and attachment basis ontowhich stator assembly 304 and rotor assembly 321 can be installed into adata storage system quickly and inexpensively. As discussed withreference to FIG. 3, motor assembly 300, before being affixed to base326, can also be radially aligned through fixturing and tacked orpartially cured using the adhesives described above. After tacking,motor assembly 300 can be fully cured in an oven.

FIG. 6 illustrates a top perspective view of a FPC 402 in accordancewith an embodiment of the present invention. FPC 402 has a top surface410 and a bottom surface (hidden from view). FPC 402 includes an endportion 406 and a pathway portion 408. End portion 406 accommodatesstator assembly 404. Pathway portion 408 provides a pathway for aninterconnect layer, integrally formed with FPC 402, to couple statorassembly 404 to a remotely located electrical connector through pathwayportion 408 for ultimate coupling to a PCB. In one embodiment, FIG. 6illustrates end portion 406 of FPC 402 as having an annular top surfacearea such that the end portion includes an outer diameter 411 and aninner diameter 413. End portion 406 of FPC 402 includes a plurality ofpatterns of conductor traces 442. Each pattern of conductor traces 442are symmetrically and radially arranged on top surface 410 of endportion 406 between outer diameter 411 and inner diameter 413. Portionsof the pattern of conductor traces 442 are exposed to top surface 410.These exposed openings are not shown in FIG. 6 because, as illustrated,a cover layer that forms top surface 410 of FPC 402 is transparent.Conductor traces 442 are included in the interconnect layer of FPC 402.However, the illustrated conductor traces 442 show only a single layerof conductor traces. Below the illustrated layer of conductor traces areother layers of conductor traces configured for use in connecting othertypes of motors having different numbers of phases. The interconnectlayer will be discussed in detail with reference to FIG. 11.

FIG. 7 illustrates a top perspective view of a portion of a motorsubassembly 401 including the FPC 402 of FIG. 6 in accordance with anembodiment of the present invention. Stator assembly 404 includes anannular stator yoke 405 coupled to a plurality of symmetrically andradially arranged stator teeth 412. Each stator tooth 412 includes a topportion 444 and side portions 446. Each stator tooth 412 is positionedadjacent and in alignment with each pattern of conductor traces 442. Endportion 406 is affixed to stator assembly 404 at top surface 410 andbetween inner diameter 413 and outer diameter 411. In one embodiment,end portion 406 is affixed to stator assembly 404 with solder. However,end portion 406 can be affixed to stator assembly 404 with othermaterials, such as adhesive.

FIG. 8 illustrates a top perspective view of motor subassembly 401illustrated partially in FIG. 7 in accordance with an embodiment of thepresent invention. Each stator tooth 412 of stator assembly 404 isconfigured to support a stator coil 414. In the embodiment illustratedin FIG. 8, each stator coil 414 includes a set of staple-shaped statorconductors 415. Each set of staple-shaped stator conductors 415 aredeposited on top portion 444 (FIG. 7) of each stator tooth 412 such thateach set of the staple-shaped stator conductors are adjacent the topportion and adjacent side portions 446 (FIG. 7) of each stator tooth.Each set of staple-shaped stator conductors 415 has a shape similar to ashape of a conventional staple which is more clearly illustrated withrespect to FIGS. 9 and 10.

FIG. 9 illustrates an enlarged perspective view of a stator tooth 412having a stator coil 414. FIG. 10 illustrates an enlarged perspectiveview of stator coil 414 shown in FIG. 11, but with the stator toothremoved for purposes of clarity. As illustrated in FIGS. 9 and 10, eachset of staple-shaped stator conductors 415 are electrically andmechanically coupled, using solder, to a corresponding pattern ofconductor traces 442 to thereby form stator coil 414. Stator coils 414electrically perform similar to the stator coils (214, 314) illustratedin FIGS. 2 and 4. However, stator coils 414 are formed of twocomponents. One of the components is the pattern of conductor traces 442and the other component is the set of stator conductors 415. Uponenergization, the electrically coupled set of stator conductors 415 andthe pattern of conductor traces 442, illustrated in FIGS. 9 and 10,generate a magnetic field. It should be noted that each staple-shapedstator conductor 415 can be in contact with each other if coated with athin insulating material. Otherwise, each staple-shaped stator conductoris spaced a distance from each other to avoid electrical shorting.

As illustrated in FIG. 9, FPC 402 is affixed to stator assembly 404 withsolder by way of staple-shaped conductors 415 being stacked on statorteeth 412 and soldered to conductor traces 442. In another embodiment,staple-shaped stator conductors 415 have a pair of prongs on their tipsinstead of a pair of feet as illustrated in FIGS. 9 and 10. In such anembodiment, the pair of prongs are inserted through openings in the topsurface and the interconnect layer of FPC 402. The interconnect layer isconfigured to receive the pair of prongs like a connector receiver. Inyet another embodiment, a separate electrical connector can be solder tothe interconnect layer of FPC 402 such that it connects thestaple-shaped conductors 415 with conductor traces 442 of theinterconnect layer. However, as previously discussed, FPC 402 can alsobe affixed to stator assembly 404 with other materials, such asadhesive.

FIG. 11 illustrates a partial sectional view of a motor assembly 400including the motor subassembly 401 illustrated in FIG. 8 in accordancewith an embodiment of the present invention. Stator assembly 404includes stator yoke 405, stator tooth 412 and stator coil 414. Statorcoil 414 includes the pattern of conductor traces (not specificallyillustrated in FIG. 11) included in interconnect layer 432 of FPC 402and a set of staple-shaped stator conductors 415. Stator assembly 404 isformed of a layered stack of magnetic steel laminations that are woundwith wire. The layered stack of steel is coated with an insulativecoating prior to winding. In addition, FIG. 11 also illustrates a base426 in which FPC 402 is affixed to. In one embodiment of the presentinvention, base 426 is a basedeck of a data storage system. However,those skilled in the art should recognize that the present invention canbe incorporated in other types of systems.

Motor assembly 400 also includes a simplified illustration of rotorassembly 421. Rotor assembly 421 includes a rotor 422 and an annularmagnet 424. Rotor assembly 421 is centrally located and deposited onbase 426 such that stator assembly 404 and the inner diameter 413 of endportion 406 are spaced apart from and positioned around rotor assembly421.

Motor assembly 400 also includes a flux shield 418 and insulating layer420. In one embodiment, flux shield 418 and insulating layer 420 areaffixed to the stapled-shaped stator conductors 415 and top portion 444of stator coil 414 with an adhesive. In a data storage system, fluxshield 418 and insulating layer 420 assists in insulating the discs ormedia from magnetic fields created by stator assembly 404 and magnet424. Flux shield 418 and insulating layer 420 are adhered to statortooth 412 which creates a “sandwich” potting of stator conductors tothereby mute acoustic output. Those skilled in the art should recognizethat other embodiments of the present invention can include a motorassembly without a flux shield.

As illustrated in detail in FIG. 11, FPC 402 includes a plurality oflayers. FPC 402 includes a cover layer 430 that forms top surface 410and includes a plurality of openings, such as openings 434, for exposingthe pattern of conductor traces 442 (formed with interconnect layer 432)to staple-shaped stator conductors 415. Staple-shaped stator conductors415 and the pattern of conductor traces (not shown in FIG. 11) formstator coil 414 that generates a magnetic field. Interconnect layer 432is located adjacent cover layer 430 and includes the pattern ofconductor traces, which form stator coils 414, and layers of traces foreach phase of motor assembly 400. FPC 402 also includes a stiffenerlayer 438 adjacent interconnect layer 432 as discussed in thedescription related to FIG. 3.

Motor assembly 400 includes an adhesive layer 440 that allows fluxshield 418, stator coils 414, stator teeth 412 and FPC 402 to be affixedto base 426. In such an embodiment, adhesive layer 440 such as a layerof PSA, also includes a liner that is formed adjacent stiffener layer438 on bottom surface 441 of FPC 402. In use, the liner is pulled backand removed to expose the adhesive for attachment. However, motorassembly 400 can be affixed to base 426 in other manners. For example,adhesive layer 440 can be replaced with a separately applied adhesive orepoxy.

Therefore, FPC 402 is used as a positioning and attachment basis ontowhich stator assembly 404 can be installed into a data storage systemquickly and inexpensively. As discussed with reference to FIG. 3, motorassembly 400 can also be radially aligned through fixturing and tackedor partially cured using the adhesives described above. After tacking,motor assembly 400 can be fully cured in an oven.

FIG. 12 illustrates a top perspective view of a motor subassembly 501 inaccordance with an embodiment of the present invention. Motorsubassembly 501 includes a FPC 502 and a stator assembly 504. FPC 502has a top surface 510 and a bottom surface (hidden from view). FPC 502includes an end portion 506 and a pathway portion 508. End portion 506accommodates stator assembly 504. Pathway portion 508 provides a pathwayfor an interconnect layer, integrally formed with FPC 502, toelectrically connect stator assembly 504 to a remotely locatedelectrical connector for ultimate coupling to a PCB. End portion 506includes a plurality of patterns of conductor traces 542. The patternsof conductor traces 542 are symmetrically and radially arranged on topsurface 510 of end portion 506. Each pattern of conductor traces 542 areformed with the interconnect layer of FPC 502. Conductor traces weredescribed in detail with respect to FIG. 6 and the interconnect layerwill be discussed in detail with reference to FIG. 13. In comparison toFPC 402 of FIG. 8, FPC 502 includes a circular top surface area suchthat the end portion includes an outer diameter 511. Unlike FPC 402 ofFIG. 8, FPC 502 does not include an inner opening.

Stator assembly 504 includes an annular stator yoke 505 coupled to aplurality of symmetrically and radially arranged stator teeth 512. Eachstator tooth 512 of stator assembly 504 is configured to support astator coil 514. Each stator tooth 512 includes a top portion 544 andside portions 546. Each stator tooth 512 is positioned adjacent and inalignment with each pattern of conductor traces 542. In one embodiment,end portion 506 of FPC 502 is affixed with an adhesive to statorassembly 504 at top surface 510. However, end portion 506 can be affixedto stator assembly 504 with other materials. For example, end portion506 can be affixed to stator assembly 504 with solder, which isdescribed in more detail below.

In the embodiment illustrated in FIG. 12, each stator coil 514 includesa set of staple-shaped stator conductors 515 and a corresponding patternof the conductor traces 542. Each set of staple-shaped stator conductors515 are deposited on top portion 544 of each stator tooth 512 such thateach set of staple-shaped stator conductors are adjacent the top portionand side portions 546 of each stator tooth. Each set of statorconductors 515 has a shape similar to a shape of a conventional staple,which was clearly illustrated and described with respect to FIGS. 9 and10.

As illustrated in the FIG. 12 embodiment, FPC 502 is affixed to statorassembly 504 with solder by way of staple-shaped conductors 515 beingstacked on stator teeth 514 and soldered to conductor traces 542. Inanother embodiment, staple-shaped stator conductors 515 have prongs ontheir tips instead of feet as illustrated in FIG. 12. In such anembodiment, the prongs insert through openings in the top surface andthe interconnect layer of FPC 502. The interconnect layer is configuredto receive the prongs like a connector receiver. In yet anotherembodiment, a separate electrical connector can be solder to theinterconnect layer of FPC 502 such that it can connect the staple-shapedconductors 515 with conductor traces 542 of the interconnect layer.However, as previously discussed, FPC 502 can be affixed to statorassembly 504 with other materials, such as adhesive.

FIG. 13 illustrates a partial sectional view of a motor assembly 500including the motor subassembly 501 illustrated in FIG. 12 in accordancewith an embodiment of the present invention. Stator assembly 504includes stator yoke 505, stator tooth 512 and stator coil 514. Statorcoil 514 includes the pattern of conductor traces (not specificallyillustrated in FIG. 13) included in interconnect layer 532 and a set ofstaple-shaped stator conductors 515. Stator assembly 504 is formed of alayered stack of magnetic steel laminations that are wound with wire.The layered stack of steel is coated with an insulative coating prior towinding. FIG. 13 also illustrates a base 526 in which FPC 502 is affixedto. In one embodiment of the present invention, base 526 is a basedeckof a data storage system. However, those skilled in the art shouldrecognize that the present invention can be incorporated in other typesof systems.

Motor assembly 500 also includes a simplified illustration of a rotorassembly 521. Rotor assembly 521 includes a rotor 522 and an annularmagnet 524. Rotor assembly 521 is centrally located and mounted on FPC502 such that stator assembly 504 is spaced apart and positioned aroundrotor assembly 521 on end portion 506.

Motor assembly 500 also includes a flux shield 518 and insulating layer520. Flux shield 518 and insulating layer 520 are affixed to top portion544 of stator tooth 512 with an adhesive. As discussed above, fluxshield 518 and insulating layer 520 assist in insulating the discs ormedia in a data storage system from magnetic fields created by statorassembly 504 and magnet 524. Flux shield 518 and insulating layer 520are adhered to stator assembly 504 which creates a “sandwich” potting ofthe stator coils to thereby mute acoustic output. Those skilled in theart should recognize that other embodiments of the present invention caninclude a motor assembly without a flux shield.

As illustrated in detail in FIG. 13, FPC 502 includes a plurality oflayers. FPC 502 includes a cover layer 530 that forms top surface 510and includes a plurality of openings 534 for exposing and allowing eachpattern of conductor traces, which are formed with and connected tointerconnect layer 532, to couple to each staple-shaped stator conductor515. At least one of the openings 534 also exposes and allowsinterconnect layer 532 to couple to rotor 522. Besides interconnectlayer 532 including layers of traces for each phase of the motorassembly, the interconnect layer also includes traces for rotor 522, thepatterns of conductor traces and a ground trace for the rotor. In oneembodiment, rotor assembly 521 is affixed to end portion 506 of FPC 502with solder 525 such that rotor 522 is electrically coupled andelectrically grounded to interconnect layer 532. However, those skilledin the art should recognize that other configurations are possible. Forexample, rotor 522 can be affixed to end portion 506 and electricallycoupled to interconnect layer 532 with an electrically conductiveadhesive.

Motor assembly 500 includes an adhesive layer 540 that allows fluxshield 518, stator coils 514, stator teeth 512 and FPC 502 to be affixedto base 526. In such an embodiment, adhesive layer 540, such as a layerof PSA, also includes a liner and is formed adjacent stiffener layer 538on a bottom surface 541 of FPC 502. In use, the liner is pulled back andremoved to expose the adhesive for attachment. However, motor assembly500 can be affixed to base 526 in other manners. For example, adhesivelayer 540 can be replaced with a separately applied adhesive or epoxy.

Therefore, FPC 502 is used as a positioning and attachment basis ontowhich stator assembly 504 and rotor assembly 521 can be installed into adata storage system quickly and inexpensively. As discussed withreference to FIG. 3, motor assembly 500 is radially aligned throughfixturing and tacked or partially cured using the adhesives describedabove. After tacking, motor assembly 500 can be fully cured in an oven.

It is to be understood that even though numerous characteristics andadvantages of various embodiments of the invention have been set forthin the foregoing description, together with details of the structure andfunction of various embodiments of the invention, this disclosure isillustrative only, and changes may be made in detail, especially inmatters of structure and arrangement of parts within the principles ofthe present invention to the full extent indicated by the broad generalmeaning of the terms in which the appended claims are expressed. Forexample, the particular elements may vary depending on the particularapplication for the motor assembly while maintaining substantially thesame functionality without departing from the scope and spirit of thepresent invention. In addition, although the preferred embodimentdescribed herein is directed to a motor assembly for a data storagesystem, it will be appreciated by those skilled in the art that theteachings of the present invention can be applied to other types ofsystems, without departing from the scope and spirit of the presentinvention.

1. A method of assembling a motor comprising: obtaining a statordefining a plurality of stator teeth; obtaining a flexible printedcircuit having an interconnect layer and a cover layer, the cover layerincluding a plurality of openings for exposing the interconnect layer;training a plurality of electrically conductive members around each ofthe stator teeth, each of the plurality of electrically conductivemembers individually circumscribing each stator tooth less than onecomplete revolution; and coupling each of the plurality of electricallyconductive members with the interconnect layer to form a coil woundaround each stator tooth.
 2. The method of claim 1, wherein the flexibleprinted circuit comprises opposing first and second surfaces and an endportion.
 3. The method of claim 2, further comprising affixing the firstsurface of the end portion of the flexible printed circuit to thestator.
 4. The method of claim 3, further comprising affixing the secondsurface of the end portion of the flexible printed circuit to a base ofwhich the motor is to be mounted.
 5. The method of claim 1, wherein eachstator tooth comprises a medial portion and a pair of side portions,each electrically conductive member being adjacent the medial portionand the side portions.
 6. The method of claim 5, wherein eachelectrically conductive member includes an intermediate segment adjacentthe medial portion of each stator tooth and a pair of side segmentsadjacent each of the respective pair of side portions of each statortooth.
 7. The method of claim 1, wherein training a plurality ofelectrically conductive members around each of the stator teethcomprises depositing a set of staple-shaped stator conductors on aportion of each of the stator teeth.
 8. The method of claim 7, whereineach staple-shaped conductor includes a pair of side segments locatedadjacent side portions of each stator tooth and an intermediate segmentthat couples the pair of side segments and is located adjacent to amedial portion of each stator tooth.
 9. The method of claim 7, whereindepositing the set of staple-shaped conductors on the portion of each ofthe stator teeth comprises depositing each staple-shaped conductor ofthe set of staple-shaped conductors a spaced distance from each otheralong each of the stator teeth.